Though everyone smiles, people from different cultures, different social locations, different historical periods ascribe different meanings to smiling (and the actual smile, the muscular event that we call smiling, varies with time and place as well). Middle Americans smile more often, and sustain their (characteristically American, and even middle class) smiles for a longer period of time than, say, Icelanders. And Icelanders often consider excessive smiling as inappropriate, perhaps ridiculous, and, in general, undesirable. Hence, McDonald’s trouble to train their Icelandic cashiers to flash those winning and protracted American smiles right and left throughout their eight-hour shift. Look at the official portraits of the US presidents in chronological order and you will see that the smiling curb starts peaking only from the middle of the 20 century on. There is a history to the meaning of smiling. And smiling is hence a sort of intermediate variable that often points not toward universal affects, but toward an array of cultural meanings that tend to change from place to place and from time to time. Thus, just as lighter ownership is not the true predictor of cancer (though having a lighter in your pocket points toward possible cancer outcomes), smiling is not at all a true predictor of marriage stability. This predictor stands behind the smile, and it includes psychological, cultural, and historical conditions that seem to be completely outside the scope of this study.